1. Field of the Invention
The invention relates to a device for the low-deformation mounting of a rotationally asymmetric optical element, in particular of an optical element in a projection lens system for semiconductor lithography, which is mounted in a frame.
2. Description of the Related Art
In particular in the case of projection lens systems in semiconductor lithography for producing semiconductor elements, it is necessary to know the precise installation position of an optical element or of an optical subassembly in relation to reference surfaces. Furthermore, it is often necessary for an optical element or a subassembly, following removal and reinstallation, to be positioned precisely in relation to the previous position, it also being intended, in particular, for the same, or at least very similar, deformation to occur as in the case of installation first time around, in order that reproducibility is achieved and there are no chances in respect of the imaging quality of the projection lens system.
A reproducible installation position and at least more or less identical deformation forces are particularly difficult to achieve in the case of rotationally asymmetric optical elements. This applies, in particular, to beam splitter cubes, prisms and double mirrors.